Culver Armature and Motor

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Tools Belt Tensioning Instructions

Belt Tensioning Instructions

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V-Belts

V-belt tensioning adjustment can be made using a tensionmeter or other type spring scale, using the following procedure. After seating the belts in the groove and adjusting center distance so as to take up slack in the belts, further increase the tension until only a slight bow on the slack side is apparent while the drive is operating under load. Stop the drive, and using the meter, measure the force necessary to depress one of the center belts 1/64-inch for every inch of belt span (see sketch below). For example, a deflection for a 50-inch belt span is 50/64ths, or 25/32-inch. The amount of force required to deflect the belt should compare with the deflection forces noted in the chart below. Also notice for V-belts that deflection forces vary from the initial "run-in" values which are greater (reflecting higher run-in tensioning) to the "normal" values for after the run-in period.

Synchronous Belts

Hign torque, Standard and Metric synchronous belts should be installed to fit pulleys snugly, neither too tight nor too loose. The belt's positive grip eliminates the need for high initial tension. When a belt is installed with a snug but not overly tight fit, longer belt life, less bearing wear and more quiet operation will result. Overtight belts can cause early failure and should be avoided. With high torque a loose belt may "jump teeth" upon startup. If such occurs, the tension should be increased gradually until satisfactory operation is achieved. To properly tension a synchronous belt, place belt on pulleys and adjust takeup until the belt teeth mesh securely with the pulley grooves. Measure belt span "T". Then tighten belt so that it deflects 1/64-inch for every inch of belt span when a force as specified in the table below is applied to the top of the belt. For belts wider than two inches, a metal or wooden strip 3/4 to 1-inch wide should be placed across the belt between it and the tester to prevent distortion. The following range of deflection forces are normally adequate for drive installation. Actual installation tension required depends on peak loads, system rigidity, number of teeth in mesh, etc.

 

How to measure pulley span length.

Measure the span lendth "t" as shown in the sketch above.

 

Standard V-Belt Tensioning Deflection Force
Belt
Cross Section
Smaller
Pulley
Diameter
Range (in.)
Deflection Force Run-in (lbs.) Deflection Force Normal
(lbs.)
A3.0-3.63-3/82-1/4
3.8-4.84-1/42-7/8
5.0-7.05-1/83-3/8
AX3.0-3.64-1/82-3/4
3.8-4.853-1/4
5.0-7.064
B3.4-4.242-5/8
4.4-5.264
5.4-9.47-1/85-1/4
BX3.4-4.25-1/43-1/2
4.4-5.27-1/84-3/4
5.4-9.496
C7.0-9.011-1/47-1/2
9.5-16.015-3/410-1/2
CX7.0-9.013-1/29
9.5-16.017-1/211-3/4
D12.0-16.024-1/216-1/2
18.0-22.03322
E21.6-27.04832
3V3.40-4.2064
4.20-10.675
3VX2.20-3.6575
4.12-10.686
5V7.10-10.9168-12
11.8-16.02010-15
5VX4.40-10.91810-14
11.8-16.02212-18
8V12.5-17.03618-27
18.0-22.44020-30

 

Synchronous Belt Tensioning Deflection Force
Belt Pitch
Belt Width Deflection Fource
Synchron. 8MM
(14mm)
20mm2 to 4 lbs
30mm3 to 6 lbs
50mm7 to 11 lbs
85mm11 to 19 lbs
Synchron. 14MM(14mm)40mm5 to 11 lbs
55mm8 to 17 lbs
85mm14 to 27 lbs
115mm20 to 40 lbs
170mm30 to 60 lbs
MXL (.080-in.)1/8-inch1 oz
3/16-inch1 - 1-1/2 oz
1/4-inch2 oz
5/16-inch2 - 2-1/2 oz
XL (1/5-in.)1/4-inch2-1/2 oz
5/16-inch3 oz
3/8-inch3-1/2 oz
L (3/8-in.)1/2-inch7 oz
3/4-inch11 oz
1-inch1 lb
H (1/2-in.)3/4-inch2 lbs
1-inch2-1/2 lbs
1-1/2-inch4 lbs
2-inch5-1/2 lbs
3-inch8-1/2 lbs
XH (7/8-in.)2-inch7-1/2 lbs
3-inch11-1/2 lbs
4-inch16-1/2 lbs
XXH (1-1/4-in.)2-inch9 lbs
3-inch14 lbs
4-inch20 lbs
5-inch26 lbs

 

Last Updated on Monday, 15 June 2009 14:58 

Hours

Monday - Friday
8AM - 12PM/1PM -  5PM
Closed For Lunch

 

1010 North D Street
Sacramento, CA 95811

P (916) 451-5858
F (916) 451-8417